Bach 1B vs Conn Imp. Precision 4
The Bach 1B has a wider cup diameter, the Bach 1B features a deeper cup.
The internal diameter of the cup, measured at the widest point inside the rim.
Mouthpiece A
Bach 1B
• Cornet
Cup diameter17.00 mm / 0.6693 in
Best suited for
Orchestral playing — large cup for full, dark tone
vs
Mouthpiece B
Conn Imp. Precision 4
• Cornet
GeneralCup diameter16.41 mm / 0.6461 in
Best suited for
All-round versatile — balanced cup for general playing
Players with large full lips; most common surviving example
Bright tone; same as Model 3 with wide rim
Cup Diameter
The Bach 1B has a cup diameter of 17.00 mm / 0.6693 in compared to 16.41 mm / 0.6461 in on the Conn Imp. Precision 4 — a difference of 0.59 mm / 0.0232 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Which is better?
Neither mouthpiece clearly dominates the other — the right choice depends on your embouchure, playing style, and the sound you're after. Try both if possible.